4R70W + Atlas II questions

[DanWheeler]

After months of research I'm getting close the pull the trigger on the 4R70W / Atlas II combo.

I'm picking up the transmission this weekend from a 2000 5.0 explorer. I'm going to grab the starter and torque converter. The flexplate won't work since I need 28oz.

Before I jump to deep into this and buy the Buamann controller and the Atlas, I just wanted to check and make sure I was on the right track.

Mostly my concerns are with driveshafts and clearance for the Atlas II.

I am expecting to need new driveshafts (currently NP435/D20 w/ 3.5" lift) but I have read that there may be clearance problems with the front driveshaft and the transmission pan.

I also read that the Atlas doesn't fit between the framerails. True/False?

So is there anyone out there who has done this conversion and knows about t-case clocking and driveshaft clearance?

anything else I should be concerned about?

thanks!
dan

 

[Broncobowsher]

I have not done the 4R70W and an Atlas, but the output shaft of the transmission should be in the same place as the original transmission. Therefor if the Atlas would normally fit in a Bronco there is no reason it should have any issues with this installation. Now if you try and clock it up higher then expect frame rail interference, but you would have the same regardless of what transmission you try and run.

 

[COBlu77]

You will be fine on the fit. You will need your rear driveshaft shortened and the front lengthened. If you keep the shift lever on the side of the tranny in the stock position (pointing upward) you should not have any front driveshaft interference with the tranny or pan, but watch for front CV bind at full droop. The pinion angle is pretty steep. You will need to adjust the pinion angle in the rear by moving your spring mounts or using angled shims.

I originally planned on a NP205 as a temporary solution and wanted an Atlas II. The Atlas II length should be within 1/2" or so of my NP205. I don't think you can clock it flat, but it should hang down slightly less than an NP205 and not much more than your D20. My NP205 hangs approximately as low as the radius arm bracket.

 

[DanWheeler]

I have not done the 4R70W and an Atlas, but the output shaft of the transmission should be in the same place as the original transmission. Therefor if the Atlas would normally fit in a Bronco there is no reason it should have any issues with this installation. Now if you try and clock it up higher then expect frame rail interference, but you would have the same regardless of what transmission you try and run.

hmm, so maybe I wont need new driveshafts? my current NP435/D20 driveshafts aren't much different than stock and if you're saying the Atlas sits about the same place as stock then maybe I'll be OK on driveshafts?

according to the FAQ page on 700r4inaford.com (http://www.700r4inaford.com/faq.html

a stock C4 is 17" long while the 4R70W is 21.375" long.

it says the adaptor for a C4 to an Atlas OR Dana 20 is 7.375"

it says the adaptor for a 4R70W to an Atlas OR Dana 20 is about 6"

I'm not sure what he means by adapter since the Atlas doesn't need an adapter to connect to

it says an Atlas is is 13.8" long and a Dana 20 is 10.5" long.

So C4/Dana 20 comes out to 34.875" long

4R70W/Atlas comes out to 41.55" long

i guess i'll just have to find out. I'll go do some measuring tonight.

 

[DanWheeler]

You will be fine on the fit. You will need your rear driveshaft shortened and the front lengthened. If you keep the shift lever on the side of the tranny in the stock position (pointing upward) you should not have any front driveshaft interference with the tranny or pan, but watch for front CV bind at full droop. The pinion angle is pretty steep. You will need to adjust the pinion angle in the rear by moving your spring mounts or using angled shims.

I originally planned on a NP205 as a temporary solution and wanted an Atlas II. The Atlas II length should be within 1/2" or so of my NP205. I don't think you can clock it flat, but it should hang down slightly less than an NP205 and not much more than your D20. My NP205 hangs approximately as low as the radius arm bracket.

awesome, thanks for the info CoBlu. When I upgraded my rear axle to a big bearing, I rotated the pinion up so I'm hoping I will be OK there.

how do you like the 4R70W with the 205?

 

[COBlu77]

awesome, thanks for the info CoBlu. When I upgraded my rear axle to a big bearing, I rotated the pinion up so I'm hoping I will be OK there.

how do you like the 4R70W with the 205?

I love the 4R70W. It really helps drivability. By far the best thing I've done. Make sure you get a good tranny cooler and temp gauge.

The NP205 is growing on me. I'd like a little lower gearing for going down really steep stuff, but have had no problem climbing steep hills or obstacles. But for $125 vs $2000 I can definately live with the NP205. The crawl ratio is almost identical to when I had a C4 and D20 and I did every trail I wanted to do with that combo. My 4R70W/NP205 is perfect for most moderate trails and will get you through the tough stuff with lockers and good brakes.

Let us know how you like the Atlas II and how it goes in.

 

[Broncobowsher]

hmm, so maybe I wont need new driveshafts? my current NP435/D20 driveshafts aren't much different than stock and if you're saying the Atlas sits about the same place as stock then maybe I'll be OK on driveshafts?

according to the FAQ page on 700r4inaford.com (http://www.700r4inaford.com/faq.html

a stock C4 is 17" long while the 4R70W is 21.375" long.

it says the adaptor for a C4 to an Atlas OR Dana 20 is 7.375"

it says the adaptor for a 4R70W to an Atlas OR Dana 20 is about 6"

I'm not sure what he means by adapter since the Atlas doesn't need an adapter to connect to

it says an Atlas is is 13.8" long and a Dana 20 is 10.5" long.

So C4/Dana 20 comes out to 34.875" long

4R70W/Atlas comes out to 41.55" long

i guess i'll just have to find out. I'll go do some measuring tonight.

I was refering to the shaft's location between the frame rails, not the CV mounting flange. I was stating that the Atlas will fit between the frame rails side to side. I made no reference to front to back.

You will expect to need driveshaft length modifications/replacments

 

[Lebe]

Before I jump to deep into this and buy the Buamann controller and the Atlas, I just wanted to check and make sure I was on the right track.

Mostly my concerns are with driveshafts and clearance for the Atlas II.

I am expecting to need new driveshafts (currently NP435/D20 w/ 3.5" lift) but I have read that there may be clearance problems with the front driveshaft and the transmission pan.

I also read that the Atlas doesn't fit between the framerails. True/False?

So is there anyone out there who has done this conversion and knows about t-case clocking and driveshaft clearance?

anything else I should be concerned about?

thanks!
dan[/QUOTE]

Mine is a transplanted '98 Explorer 5.0L with 4R70W and Atlas 4. Atlas fit between the rails if the whole thing is slightly cocked to pass. side. No driveshaft interference to D60 front. Probably need new drive shafts though.

 

[Broncobowsher]

As I stated, the Atlas should fit just fine. You are not changing the centerline of the transmission and the framerails are not getting any narrower. There a little bit of give in that you can rotate the engine on the motor mount perches to push it over to the passenger side to gain a little more room if need be.

What I can't answer is the driveshaft to pan clearance. I know the D20 likes to run a 2" shaft to clear the pan. I think the Atlas is a bit wider between centerlines so that should make for more clearance.

 

[DanWheeler]

Mine is a transplanted '98 Explorer 5.0L with 4R70W and Atlas 4. Atlas fit between the rails if the whole thing is slightly cocked to pass. side. No driveshaft interference to D60 front. Probably need new drive shafts though.

how'd you do the 5.0 explorer conversion? The motor is also available from the explorer I'm getting the 4R70W from but from the reading I did it sounded like converting the explorer 5.0 would be really complicated.

 

[OsideDave]

I have not done your conversion. But I did do a C4 STaK 3 speed combo and other things to consider is headers and crossmember. Longtube headers will likely not fit and crossmember may have to be fabbed. I believe Tom's has crossmember to fit AOD/4r70W and depending on clocking position it may or maynot interfer w/ front driveshaft. My 2 cents on other things to consider.

 

[DanWheeler]

I talked to someone at Tom's and they said the AOD crossmember would not work for the 4R70W. I have no idea why but they weren't very helpful - just said it wouldn't work.

I figure anything can work with enough steel and welding. Maybe they just meant it wouldn't bolt right in?

I wish I knew why it "won't work" so I could determine if I could make it work for me.

 

[DanWheeler]

ok, i called someone at Tom's and they were very helpful and said the crossmember they sell is basically a stock bronco crossmember notched in the middle to clear the tranny pan. I guess I'll have to wait and see if my stock crossmember will work with the Atlas.

 

[Broncobowsher]

Sounds like you are not realizing the non-interchangability between the AA AOD to D20 crossmember which uses stock Bronco bushings to the completely different, single rubber foot late model transmission mount style.

I thought there was a post that stated the ZF crossmember would work with the 4R70W (providing you used the stock adaptor for the full size transfer case and not the AA D20 adaptor)